CN116516488A - A second-order nonlinear optical crystal material of fluorocerium-based sulfate and its preparation and application - Google Patents

Abstract

The invention relates to a fluoro cerium-based sulfate second-order nonlinear optical crystal material, and preparation and application thereof, wherein the chemical formula of the crystal material is Ce ₃ F ₄ (SO ₄ ) ₄ Molecular weight 880.60, monoclinic system, space group C2, unit cell parametersα＝90°，β＝96.67-96.87 DEG, gamma=90 DEG, Z=2, unit cell volume isThe crystal Ce of the invention ₃ F ₄ (SO ₄ ) ₄ The powder SHG coefficient is KH under 1064nm laser irradiation ₂ PO ₄ 1.0 times of (KDP) and can realize phase matching under 1064nm laser irradiation, which shows that the method has wide application prospect in the fields of laser frequency conversion, photoelectric modulation, laser signal holographic storage and the like.

Description

A second-order nonlinear optical crystal material of fluorocerium-based sulfate and its preparation and application application

technical field

The invention belongs to the technical field of nonlinear optical crystal materials, and relates to a second-order nonlinear optical crystal material of fluorocerium sulfate and its preparation and application.

Background technique

The typical feature of the second-order nonlinear optical crystal is the frequency doubling effect (SHG). It is an important photoelectric functional material and has important application prospects in the fields of laser frequency conversion, photoelectric modulation, and laser signal holographic storage. Currently commercialized nonlinear optical materials include BBO (β-barium metaborate), LBO (lithium borate), KDP (potassium dihydrogen phosphate), and KTP (potassium titanyl phosphate). With the development of laser technology and the emergence of tunable lasers, nonlinear optical devices have developed rapidly, and laser frequency doubling, frequency mixing, parametric oscillation and amplification; electro-optical modulation, deflection, Q-switching and photorefractive devices have appeared one after another. The above studies and applications have put forward more and higher requirements for physical and chemical properties of nonlinear optical materials, but the current development of nonlinear optical materials is still difficult to meet their requirements. Therefore, it is necessary to continuously develop new types of nonlinear optical materials. crystals.

Contents of the invention

The purpose of the present invention is to provide a second-order nonlinear optical crystal material of fluorocerium sulfate and its preparation and application. The prepared crystal shows a strong frequency doubling effect, and its powder SHG effect is 1 times that of KDP The above, and can achieve phase matching, is a nonlinear optical material with potential application value.

The purpose of the present invention can be achieved through the following technical solutions:

One of the technical solutions of the present invention provides a second-order nonlinear optical crystal material of fluorocerium-based sulfate, whose chemical formula is Ce ₃ F ₄ (SO ₄ ) ₄ , belongs to the monoclinic crystal system, and its space group is C2, The cell parameters are α=90°, β=96.67°～96.87°, γ=90°, Z=2, the unit cell volume is />

The crystal structure of the fluorosulfate of the present invention is as follows: two crystallographically independent Ce ions coordinate with five ^oxygen atoms, three fluorine atoms and six oxygen atoms, two fluorine atoms respectively to form [Ce( 1) O ₅ F ₃ ] and [Ce(2)O ₆ F ₂ ] two polyhedrons, in which adjacent Ce(1) and Ce(2) atoms are connected by F(2) atoms, and adjacent Ce(1) and Ce(1) atoms are bridged by F(1), thus forming a two-dimensional [Ce ₃ F ₄ ] _∞ layered plane. Two crystallographically independent [SO ₄ ] groups cover the adjacent [Ce(1)O ₅ F ₃ ] and [Ce(2)O ₆ F ₂ ] polyhedra to form a three-membered ring, and further As an interlayer linker, thus forming the final three-dimensional structure.

The second technical solution of the present invention provides a method for preparing a fluorocerium-based sulfate second-order nonlinear optical crystal material. The cerium source, the sulfur source, the fluorine source, and water are mixed to form an initial mixed raw material, and then the hydrothermal crystallization under certain conditions to obtain the target product.

Further, the cerium source is cerium oxide or cerium sulfate.

Further, the sulfur source is sulfuric acid.

Further, the fluorine source is strontium fluoride.

Further, the addition amount of the cerium source, sulfur source, fluorine source and water satisfies: the molar ratio of cerium element, sulfur element, fluorine element and water in the initial mixed raw material is 1: (0.5-40): (0.5-50 ): (1~100). Preferably, the molar ratio of cerium, sulfur, fluorine and water is 1: (0.5-40): (0.5-50): (1-100); more preferably, cerium, sulfur, fluorine and The molar ratio of water is 1:(1-10):(2-20):(5-30).

Further, the temperature of the hydrothermal condition is 150-230° C., and the time is not less than 24 hours. Preferably, the hydrothermal condition temperature is 180-230° C., and the crystallization time is not less than 48 hours.

Further, after the crystallization is completed, a cooling treatment is performed at a cooling rate of 0.5-15° C./h. Preferably, the cooling rate is 0.5-6°C/h.

The third technical solution of the present invention provides the application of fluorocerium sulfate second-order nonlinear optical crystal material, which is used for frequency conversion output of visible infrared laser. Specifically, it can be applied to laser frequency converters, such as for outputting visible light and infrared laser beams with double frequency harmonics. The fluorinated cerium-based sulfate crystal material of the present invention has relatively large frequency doubling effect, and its powder frequency doubling effect is about 1.0 times that of KDP crystal under 1064nm laser irradiation, and phase matching can be realized. Furthermore, this crystalline material has a band gap of 2.50eV and a thermally stable temperature of 260oC. Therefore, the crystal material has broad application prospects in the field of nonlinear optics.

Further, the crystal material is used in frequency multiplication generators, optical parametric oscillators, optical parametric amplifiers and photoelectric rectifiers.

Compared with the prior art, the present invention has the following advantages:

(1) The crystal material of the present invention has a large frequency doubling effect, which is about 1.0 times the frequency doubling intensity of the KDP crystal under 1064nm laser irradiation, and can achieve phase matching. In addition, the crystal material has a wide transmission range in the ultraviolet-visible light region and infrared light region, the band gap is 2.50eV, and the thermal stability temperature reaches 260oC. It has broad applications in the fields of laser frequency conversion, photoelectric modulation, and laser signal holographic storage. application prospects;

(2) The present invention adopts a hydrothermal method with mild reaction conditions. At a temperature of 150-230oC, high-purity crystalline samples can be obtained with high yield through hydrothermal crystallization. The method is simple and the conditions are mild, which is conducive to the realization of large-scale Industrial production;

(3) The fluorocerium-based sulfate crystal material of the present invention can be applied to laser frequency converters, and can be used to output visible and infrared laser beams with double frequency harmonics.

Description of drawings

Fig. 1 is the crystal structure schematic diagram of fluorocerium sulfate;

Fig. 2 is the comparison of X-ray diffraction patterns; Wherein (a) is the crystal structure that sample 1# resolves according to single crystal X-ray diffraction data, the X-ray diffraction pattern that simulation obtains; (b) is that sample 1# is ground into powder and used Spectrum obtained by X-ray diffraction test;

Fig. 3 is the ultraviolet-visible-near-infrared absorption spectrum of sample 1#;

Fig. 4 is the infrared spectrum (2.5～25 μm) spectrum of sample 1#;

Fig. 5 is the thermogravimetric analysis collection of samples of sample 1#;

Figure 6 is the second harmonic signal diagram of sample 1# and KDP sample size in the range of 105-150 μm;

Fig. 7 is the second harmonic phase matching diagram of sample 1# in the 1.064μm band.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

In each of the following examples, if there is no special description of raw materials or processing techniques, it is indicated that they are conventional commercially available raw materials or conventional processing techniques in the art.

Mix cerium source, sulfur source, fluorine source and water according to a certain ratio to form starting materials, seal them in a hydrothermal reaction kettle with a polytetrafluoroethylene liner, raise the temperature to the crystallization temperature, keep the temperature for a period of time, Slowly lower the temperature of the reaction system to room temperature, filter and wash to obtain transparent blocky fluorocerium sulfate crystals.

The relationship between the types and proportions of raw materials in the initial mixture, crystallization temperature, crystallization time and sample number is shown in Table 1.

Table 1 Correspondence between samples, raw materials and synthesis conditions

Example 2:

Crystal structure analysis

The structures of samples 1# to 6# were analyzed by single crystal X-ray diffraction and powder X-ray diffraction.

The single crystal X-ray diffraction test was carried out on a D8 VENTURE CMOS X-type X-ray single crystal diffractometer from Bruker, Germany. The crystal size is 0.12×0.07×0.06mm ³ ; the data collection temperature is 293K, and the diffraction light source is Mo-Kα ray monochromated by graphite The scanning method is ω; the data is processed by the Multi-Scan method for absorption correction. Structural analysis is completed using the SHELXTL-97 program package; the position of heavy atoms is determined by the direct method, and the coordinates of the remaining atoms are obtained by the difference Fourier synthesis method; the coordinates and anisotropy of all atoms are refined by the full-matrix least squares method based on F ² thermal parameters.

The powder X-ray diffraction test was carried out on the Bruker D8 X-ray powder diffractometer of the German Bruker company. The test conditions were fixed target monochromatic light source Cu-Kα, wavelength The voltage and current are 40kV/20A, the slits DivSlit/RecSlit/SctSlit are 2.00deg/0.3mm/2.00deg respectively, the scanning range is 5-70°, and the scanning step is 0.02°. Ce ₃ F ₄ (SO ₄ ) ₄ , with a molecular weight of 880.60, belongs to the monoclinic crystal system, its space group is C2, and its unit cell parameters are α=90°, β=96.67°～96.87°, γ=90°, Z=2, the unit cell volume is />

Among them, the single crystal X-ray diffraction test results show that samples 1# to 6# have the same chemical structural formula and crystal structure, the chemical formula is Ce ₃ F ₄ (SO ₄ ) ₄ , the molecular weight is 880.60, and they belong to the monoclinic crystal system. The group is C2, and the unit cell parameters are α=90°, β=96.67°～96.87°, γ=90°, Z=2, the unit cell volume is />

Taking sample 1# as a typical representative, its crystal structure data is α=90°, β=96.773°, γ=90°, Z=2, the unit cell volume is /> Its crystal structure is shown in Figure 1.

The powder X-ray diffraction test results show that in the powder XRD spectra of samples 1# to 6#, the peak positions of each sample are basically the same, and the peak intensities are slightly different.

Take sample 1# as a typical representative, as shown in Figure 2. In Fig. 2(a), sample 1# is ground into powder and obtained by X-ray diffraction test, and Fig. 2(b) is based on the crystal structure analyzed by its single crystal X-ray diffraction, and the X-ray diffraction pattern obtained by simulation, the peak The positions and peak intensities are consistent, indicating that the obtained samples are of high purity.

Example 3:

UV Diffuse Reflectance Spectroscopy Test

The diffuse reflectance absorption spectrum test of sample 1# was carried out on a Cary 5000 UV-Vis-NIR spectrophotometer from Agilent Corporation, USA. The results are shown in Figure 3, from which it can be seen that the compound has a wide optical transmission range, and the optical band gap is 2.50eV.

Example 4:

Infrared spectrum test

The infrared spectrum test of sample 1# was carried out on a Nicolet iS10 Fourier transform infrared spectrometer of Thermo Fisher Scientific Co., Ltd., USA. The results are shown in Figure 4, from Figure 4 it can be seen that the compound has a wide range of optical transmission.

Example 5:

Thermogravimetry

The thermogravimetric test of sample 1# was carried out on a Netzsch STA 409PC thermogravimetric analyzer of Germany Netzsch Equipment Manufacturing Co., Ltd. The results are shown in Figure 5. It can be seen from Figure 5 that the compound can be stabilized up to 260oC and has good thermal stability.

Embodiment 6:

Frequency doubling test experiment and results

The frequency doubling test experiment of sample 1# is as follows: the laser with a wavelength of 1064nm generated by a Q-switched Nd:YAG solid-state laser is used as the fundamental frequency light, and the crystal powder to be tested is irradiated, and the second harmonic generated by the photomultiplier tube is used to detect, Use an oscilloscope to display the harmonic strength. The crystal sample and the control sample KDP crystal were ground separately, and the crystals with different particle sizes were sieved with a standard sieve. , 200-280 μm. Observe the trend of the multiplier signal strength changing with the particle size to judge whether it can achieve phase matching. Under the same test conditions, compare the second harmonic intensity generated by the sample and the KDP sample, so as to obtain the relative size of the frequency doubling effect of the sample.

The test results show that the compound fluorocerium sulfate crystal has a large frequency doubling effect. Under 1064nm wavelength laser irradiation, the frequency doubling signal intensity is 1.0 times that of the control sample KDP crystal (as shown in Figure 6), and phase matching can be achieved (as shown in Figure 7).

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A second-order nonlinear optical crystal material of fluorocerium-based sulfate, characterized in that its chemical formula is Ce ₃ F ₄ (SO ₄ ) ₄ , belongs to the monoclinic system, its space group is C2, and the unit cell parameters for α=90°, β=96.67°～96.87°, γ=90°, Z=2, the unit cell volume is /> 2. the preparation method of a kind of fluorocerium-based sulfate second-order nonlinear optical crystal material as claimed in claim 1, is characterized in that, cerium source, sulfur source, fluorine source and water are mixed to form initial mixed raw material, Then crystallize under hydrothermal conditions to obtain the target product. 3 . The preparation method of a fluorocerium-based sulfate second-order nonlinear optical crystal material according to claim 2 , wherein the cerium source is cerium dioxide or cerium sulfate. 4 . 4 . The preparation method of a fluorocerium-based sulfate second-order nonlinear optical crystal material according to claim 2 , wherein the sulfur source is sulfuric acid. 5 . The method for preparing a fluorocerium sulfate second-order nonlinear optical crystal material according to claim 2 , wherein the fluorine source is strontium fluoride. 6. the preparation method of a kind of fluorocerium-based sulfate second-order nonlinear optical crystal material according to claim 2, is characterized in that, the addition amount of described cerium source, sulfur source, fluorine source and water satisfies: initial The molar ratio of cerium element, sulfur element, fluorine element and water in the mixed raw material is 1:(0.5-40):(0.5-50):(1-100). 7. The method for preparing a fluorocerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that the temperature of the hydrothermal condition is 150-230° C., and the time is not less than 24 hours. 8. A method for preparing a fluorocerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that, after the crystallization is completed, cooling treatment is carried out at a cooling rate of 0.5-15°C/h . 9. The application of the second-order nonlinear optical crystal material of fluorocerium sulfate as claimed in claim 1, characterized in that the crystal material is used for frequency conversion output of visible infrared laser. 10. the application of fluorocerium sulfate second-order nonlinear optical crystal material according to claim 9, is characterized in that, this crystal material is used for frequency multiplication generator, optical parametric oscillator, optical parametric amplifier and photoelectric rectifier middle.